fix: Have an addIcon that adds to both ui and ui-next (#4490)

platform/docs/docs/migration-guide/3p8-to-3p9/2-Renamings.md

@@ -26,3 +26,8 @@ Find and replace
     @ohif/extension-default.panelModule.measurements
   </TabItem>
 </Tabs>
+
+## addIcon from ui
+
+The addIcon from the ui package has had a version added in the default extension as
+`utils.addIcon` which adds to both `ui` and `ui-next`.

platform/ui-next/src/components/Icons/Icons.tsx

@@ -2866,4 +2866,12 @@ export const Icons = {
   'icon-chevron-patient': (props: IconProps) => Icons.ChevronPatient(props),
   info: (props: IconProps) => Icons.Info(props),
   settings: (props: IconProps) => Icons.Settings(props),
+
+  /** Adds an icon to the set of icons */
+  addIcon: (name: string, icon) => {
+    if (Icons[name]) {
+      console.warn('Replacing icon', name);
+    }
+    Icons[name] = icon;
+  },
 };